This extension adds a lot of custom Anti-Debug and debugger detection to PECompact.
It also hooks the IsDebuggerPresent Api to make the Api rather more useful for Debugger detection.

More than just Debuggers, this extension also detects program monitors, crack tools (ImpRec etc), and unpackers.

Unfortunately I cannot list the debuggers/monitors/unpackers that are detected, as that would make it too easy to reverse! :)
But it detects OllyDbg, Immunity Debugger, various OllyDbg plugins, 10+ other debuggers and any unknown debuggers.
My many years of experience with executable protection has been used to create this extension.